Road surfacing machines

ABSTRACT

A road surfacing machine having two parallel material distributing screws provided one behind the other driven from their ends with the trailing screw coupled to the forwardly disposed screw and the two screws consisting of a single work unit for distributing material in the same direction. One of the two screws is vertically displaceable relative to the other.

United States Patent Leister 1 Oct. 24, 1972 [54] ROAD SURFACINGMACHINES 2,138,828 12/1938 Barber ..94/45 R 2 041,350 5/1936 Johnson..94/44 72 l ntr. Gehard Lester Bk f1d,G l 1 r en e er 3,403,609 10/1968Bradshaw ..94/46 R 3,137,220 6/1964 Smith ..94/46 R Asslgneel -W k L, Wr, 2,289,168 7/1942 Barber ..94/46 R many 22 Filed: Dec. 21 970 PrimaryExaminer-Jacob L. Nackenofi' Att0rneyWatson, Cole, Grindle & Watson [21]App1.No.: 99,834 1 [57] ABSTRACT Q Foreign Application Priority Data Aro'adsurfacing machine having two parallel material Dec. 27, 1969Germany P 19 65 141 3 distributing screws provided one behind the otherdriven from their ends with the trailing screw coupled 52] US. Cl..94/46 to the forwardly disposed Screw and the two screws [51] Int. Cl...E01c 19/48 consisting of a single work unit for distributing materi-[58] Field of Search... ..94/40, 44, 45,46 al in the ame direction. Oneof the two screws is vertically displaceable relative to the other.References Cited UNITED STATES PATENTS 6 Claims, 3 Drawing Figures2,069,376 2/1937 Madsen ..94/40 6 if g The invention relates toroad-surfacing machines, comprising two parallel material distributingscrews, disposed one behind the other, are vertically displaceablerelative to each other and are driven-from their ends.

In known equipment of this kind, the material distributing screws areencased in completely separate compartments and the material ispresented to the right-hand side of the machine in heaps. The presentedmaterial is then distributed over the entire width of the machine by thefront screw which rotates in a separate housing. The material is thusmoved to the left, and the excess material at the end is moved leftwardsby socalled paddles and through an opening in a front smoothing boardinto the separate compartment containing the rear distributing screw,which in turn distributes the delivered quantity of material to theright and then ejects the excess material through an opening. Thus, thetwo material-distributing screws, disposed one behind the other, actsuccessively in distributing the material. This system of moving excessmaterial involves the use of considerable power and of necessity resultsin heavy expensive mechanisms.

The present invention is based upon the idea of limiting thedistribution or displacement of material to the amount effectivelyrequired for making a good roadsurface. In other words, the quantitiesof material moved are matched torequirements so as to enable the powerof the drive mechanism to be reduced and, for practical purposes, toobviate the need for shifting excess quantities.

In accordance with the invention, it is proposed to achieve this objectby hinging the trailing screw to the forwardly disposed screw, and byconstituting the two screws as a single working unit for distributingthe material in the same direction. The two screws form one working unitby co-operating in moving and distributing the material in the samedirection. For this purpose, the turns of the distributing screws are ofopposite hand and the screws rotate in opposite directions.

In a preferred embodiment of the invention, the distributing screws arecoupled one to the other by means of common bearing housing in which arealso accommodated meshing gears for driving the distributing screws.

In a particular embodiment of the invention, the twin screw is dividedinto two separately operating working units by dividing both feed screwsof the twin arrangement into halves and by each of the oppositelydisposed halves of the screws having opposite threads and being drivenin opposite directions. In this arrangement, the halves of the screwlying to the rear of the assembly is hinged to the halves of theforwardly disposed screw.

For the purpose of vertically displacing the halves of the rearwardlydisposed screw there are provided independent adjusting means which,depending upon the size of the road-surfacing machine, can be operatedmanually or driven by suitable mechanical, hydraulic, pneumatic orelectrical means.

The working units of the twin screw arrangement are driven by way of theinner ends of the forwardly disposed screw which is mounted on the mainbody and which at its outer carries carrier gear wheels which mesh withgear wheels on the outer ends of the halves of the rearwardly disposedscrew. The meshing gear wheels are accommodated in end housing mountedto swing about the axis of the forwardly disposed screw.

Road-surfacing equipment embodying the invention offers the advantagethat the two working units comprising the twin screw arrangement can bereadily adjusted to suit the particular surfacing conditions. The heightof the vertically displaceable half-screws disposed towards the rear ofthe support for the equipment will depend upon the particular thicknessof surface to be laid. When varying amounts of surfacing materials arerequired, the working units constituted by the twin screws can be set atdifferent heights.

Further details and advantages of the invention will appear from thefollowing description of a preferred embodiment given by way of exampleand, illustrated in the accompanying drawings, in which:

FIG. 1 is a side-view of a machine for laying a blacktop surface andshows the twin screw of the invention in the operating position forlaying the surface,

FIG. 2 is a schematic plan view of the twin screw, and

FIG. 3 is a sectional view of a height-adjusting means on one of thehalves of the trailing screw.

The machine for laying black top surfaces illustrated in FIG. 1 iscarried by a tracked vehicle 1, and its two main groups consist of themain body 2 and a structure 3 for supporting the equipment which islinked to the main body by meansof two beams 4 pivoted as at 5 on bothsides of the body, the height of which can be adjusted.

In addition to the track 1, the main body 2 contains further principalparts, namely a drive motor 6 together with gears and transmissionelements disposed within the frame of the machine, a container 7 for thesurfacing material, a conveyor belt 8 and, at the end of themachine-frame, a twin screw 9 for the transverse distribution of thesurfacing material in front of the surfacing implements carried by thesupport 3.

The components and implements of importance in the surfacing operationare suspended from the support 3 and can be set in positions to suit thecross-section of the surface to be laid. These components and implementsare an inclined front wall 10, a tamping board or impact blade 12 whichis moved upwards and downwards by means of an eccentric shaft 11, and asmoothing board 14 which is heated by a burner 13 and which is alsocaused to vibrate by a vibrating mechanism 15.

The mixed material used for the surfacing is delivered into thecontainer 7 from a supply vehicle, not illustrated, but which mayconveniently be a dump truck. While the tracked vehicle 1 moves thesurfacing machine in the direction 16 in which the surface is to beapplied, the conveyor belt 8 continuously draws material from thecontainer 7 and deposits it on the ground behind the main body 2 and infront of the twin screw 9.

The twin screw 9 consists of two screws A and B arranged parallel to,and alongside, each other, these screws also being illustrated in FIG.2. Both screws are divided at the middle. The height of the forwardlydisposed screw A is fixed to match the greatest possible thickness ofsurface material. Its two halves are secured to the frame of the mainbody 2 by means of brackets 20, 21 and 22. Provided at both outer endsof the screw A are end housings 17 which also contain the transmissionelements by which the trailing screw B is rotated at the same speed as,but in the opposite direction to, the forward screw A, as shown by thearrows l8 and 19. The two halves of screw B are adapted to be adjustedvertically upwards and downwards, relative to the two correspondinghalves of the forward screw A, being supported at their inner endsthescrew B halves being supported at their outer ends in the two endhousings 17 and by means of bearing brackets 35 which are swingablymounted further inwards on both sides of the middle bracket 21. For thepurpose of obtaining the required vertical setting of the halves of thescrew B, elevating spindles 23 and 24, supported at the outer ends ofscrew halves B by cantilever arms 40 and at the inner ends of screwhalves B by cantilever arm 40' secured to bracket 22 (FIG. 3), securedto the equipment, are provided at both ends of the halves, the spindleshaving at their lower ends bottom hearings in which the half-screws Bare rotatably mounted, while the upper ends of the spindles co-operatewith nuts 43 carrying grips or hand-wheels'42 and held in hinge-pinrings 44. The pins 45 on these hinge-pin rings pass through holes 46 inthe cantilever arms 40 and 40 secured to the equipment. Adjusting rings47 are used for longitudinally positioning the nuts 43 and for fixingthe lateral positions of the spindle bottom bearings 41. in this way,the half-screws can be vertically set by rotating the nuts 43, thehalf-screws B being raised or lowered depending upon the direction ofrotation. The nuts 43 and spindles 23, 24 can participate in theswinging movement of the half-screws B about the halfscrews A because ofthe pivotal mounting of the nuts 43 spindles 23 and 24 therefore pivotabout pins 45 during vertical adjustment of screw halves B toaccommodate engaging gears 29. Any other suitable mechanical, hydraulic,pneumatic or electromechanical actuating means can of course be used toadjust the height of the two halves of the rear screw B independently,to suit the thickness of the required surfacing layer.

In the embodiment illustrated in FIG. 1, the screw B is shown moved to alow position on the assumption that a small thickness of surfacingmaterial is to be laid. As illustrated in the drawing, the transversemovement of the surfacing material deposited on the ground is achievedin the space 25 between the two screws A and B. The screw B allows onlyas much material to pass beneath it as is required for a surface layerof the intended thickness. In this way, the hitherto usual large heap ofmaterial in front of the front wall of the support 3 for the equipmentis avoided, and the tractive forces required in the drive for advancingthe road-surfacing machine are advantageously reduced, and this leads toimproved use of the machine particularly when the working widths aregreat and the sub-soil is unreliable.

1n the schematic illustration provided by FIG. 2, the arrangement of thetwin screw 9 is shown in plan view. Both halves of the screw A aredriven individually in arallel to the screw A can each be driven in 0site irections, as indicated by the corresponding hfise s of the screw Athrough pairs of gears 29 and 30 disposed at the ends in the housings17. FIG. 2 also shows that the threads 31 and 32 of the two halves ofthe front screw A are of opposite hand. The threads 33 and 34 of each ofthe parallel halves of the screw B again are of opposite hand to thethreads 31 and 32, i.e., the hand of the thread 33 is opposite to thatof the thread 31, and the hand of the thread 34 is opposite to that ofthe thread 32. As a result of these opposite directions of the threadsof the screws, the surfacing material passed to the middle of theequipment in front of the two halves of the twin screws is moved awayfrom the middle of the equipment on both sides of the road-surfacingmachine and is distributed uniformly over the width of the surfacing runsince it is dispensed at a rate corresponding to the vertical setting ofthe rear screw B.

What is claimed is:

l. A road surfacing machine including a frame and two parallel materialdistributing screws constituting an operating unit for the distributionof surfacing material in the same direction, a gear wheel mounted atopposite ends of each said screw, respective pairs of said gear wheelsbeing in meshing engagement at said opposite ends, means for rotatingsaid screws, one of said screws being disposed behind the other in thedirection of machine travel, means for mounting said one screw forvertical adjustment relative to said other screw, so that said one screwwill distribute surfacing material at a different level as compared tosaid other screw, said means including a spindle pivotally mounted atone end near opposite ends of said one screw, the other end of each saidspindle being pivotally mounted to said frame, and means cooperatingwith each said spindle for effecting the vertical adjustment of said onescrew relative to said other screw.

2. The machine according to claim 1 wherein each said distributing screwhas screw threads of opposite pitch with respect to one another.

3. The machine according to claim 1 wherein a common housing is providedfor each said pair of gear wheels.

4. The machine according to claim 1 wherein each of said screwscomprises a pair of screw sections, bearing bracket means on said framebeing provided for the inner ends of each said section.

5. The machine according to claim 4 wherein another spindle is pivotallymounted at one end near said inner ends of each said section of said onescrew whereby each said section of said one screw is independentlyadjustable vertically relative to their respective sections of saidother screw.

6. The machine according to claim 5 wherein said drive means includemeans for driving each pair of said screw sections independently of oneanother.

1. A road surfacing machine including a frame and two paraLlel materialdistributing screws constituting an operating unit for the distributionof surfacing material in the same direction, a gear wheel mounted atopposite ends of each said screw, respective pairs of said gear wheelsbeing in meshing engagement at said opposite ends, means for rotatingsaid screws, one of said screws being disposed behind the other in thedirection of machine travel, means for mounting said one screw forvertical adjustment relative to said other screw, so that said one screwwill distribute surfacing material at a different level as compared tosaid other screw, said means including a spindle pivotally mounted atone end near opposite ends of said one screw, the other end of each saidspindle being pivotally mounted to said frame, and means cooperatingwith each said spindle for effecting the vertical adjustment of said onescrew relative to said other screw.
 2. The machine according to claim 1wherein each said distributing screw has screw threads of opposite pitchwith respect to one another.
 3. The machine according to claim 1 whereina common housing is provided for each said pair of gear wheels.
 4. Themachine according to claim 1 wherein each of said screws comprises apair of screw sections, bearing bracket means on said frame beingprovided for the inner ends of each said section.
 5. The machineaccording to claim 4 wherein another spindle is pivotally mounted at oneend near said inner ends of each said section of said one screw wherebyeach said section of said one screw is independently adjustablevertically relative to their respective sections of said other screw. 6.The machine according to claim 5 wherein said drive means include meansfor driving each pair of said screw sections independently of oneanother.